Roll the eDice!

During my miss spent youth I've built quite a few electronic projects,
not all of which worked. One of the early ones that did work
was an electronic dice. Well, worked after a fashion: the schematics
called for a seven segment display, but the boys at the local
radioschack sold me a bar of seven LEDs! No wonder I never rolled a
one...the schematics are on the left, if you are interested.

Later I've built atleast three more to my
own design. Unfortunatelly I have no photos or schematics any
more...except this one, which
was designed to be used by my father in his teaching job. Chrisse had
designed one that had remarkably few parts, however, it displayd the
number two not diagonally as a proper dice should, but horizontally.
That just was not good enough for me.

So I started to play around with the idea and came up with
this design, Chrisse put in the finalising touches; the schematics are
his handwriting. He innovted the auto-off desing and the gradually
slowing roll action. The design features:

auto off

'real' dice patterns

gradual slow-down

few parts

just two ICs

syncronous desing

The one in the animation still runs after some eight years. It was
built by my daughther Sandra with some help from me. Below you see the
original prototype.

Kusti, 1.9.2004

P.S.

This design actually has one flow. Can you spot it? The dice
is more likely to stop at some numbers than others because because the
current consumption of the LEDs modula the thresshold of the NAND-gate
that functions as the oscillator. To cure that it is necessary to add a
power supply regulator.